8. The Highway for Rooftops

In July 1927, Popular Science profiled a proposal for a 16-mile elevated highway that would span the rooftops of a Manhattan avenue. This futuristic plan came from the mind of John K. Hencken, a New York based engineer, and was allegedly “approved by a number of eminent engineers and city planners.” Read more about this plan that called for a series of uniform twelve-story buildings extending from the Battery Park to Yonkers.